Hanging bosh construction with means allowing for thermal expansion

ABSTRACT

An iron smelting blast furnace having a plurality of annular bosh bands girdling the refractory brick walls of the bosh portion of the furnace such that each bosh band is slightly larger in diameter than the bosh band therebelow, wherein the uppermost bosh band is secured to the furnace mantle ring structure, and each lower bosh band releasably suspended from the bosh band thereabove, so that removal of a lower bosh band will not require removal of bosh bands thereabove. In addition, the means by which each lower bosh band is suspended from the bosh band thereabove is adjustable to facilitate expansion of the bosh bands upon initial furnace heat-up.

United States Patent Hollingsworth [is] 3,682,457 [45] Aug. 8, 1972 [54] HANGING BOSH CONSTRUCTION WITH MEANS ALLOWING FOR THERMAL EXPANSION inventor:

Assignee:

Filed:

Appl.

Ill.

Oct. 9, 1970 Willis W. Hollingsworth, Naperville,

United States Steel Corporation US. Cl. ..266/25, 263/44, 266/32 Int. Cl. ..C21b 7/00, C2lb 7/10 Field of Search ..266/25, 32, 43; 263/29, 44

Primary Examiner-Robert D. Baldwin Att0mey--Forest C. Sexton ABSTRACT An iron smelting blast furnace having a plurality of annular bosh bands girdling the refractory brick walls of the bosh portion of the furnace such that each bosh band is slightly larger in diameter than the bosh band therebelow, wherein the uppermost bosh band is secured to the furnace mantle ring structure, and each lower bosh band releasably suspended from the bosh band thereabove, so that removal of a lower bosh band will not require removal of bosh bands thereabove. In addition, the means by which each lower bosh band is suspended from the bosh band thereabove is adjustable to facilitate expansion of the bosh bands upon initial furnace heat-up.

4 Claim, 5 Drawing Figures HANGING BOSH CONSTRUCTION WITH MEANS ALLOWING FOR THERMAL EXPANSION BACKGROUND OF THE INVENTION The vertical shaft in substantially all iron smelting blast furnaces consists of three major portions; the stack where the furnace charge is preheated, the bosh where melting conunences, and the hearth where the molten iron and slag collect. The bosh walls, shaped like an inverted conical frustum, rest on top of the vertical side-walls of the hearth, just above the tuyere line, and extend upward with increasing diameter to the level of maximum shaft diameter at the mantle or belt, i.e., the lower cylindrical portion of the stack.

The construction of the bosh walls typically consists of refractory brick, and hollow cooling plates, supported by a plurality of steel bosh bands surrounding the outside periphery. The refractory bricks are laid in a plurality of annular sections called courses with each group of courses slightly stepped, i.e., slightly larger in diameter than the group of courses below, thereby efiecting the inverted conical frustum configuration. lndividual bosh bands provide lateral structural support by girdling the outer periphery of each group of brick courses. Therefore, each bosh band is slightly larger in diameter than the one therebelow. Although the specific details of supporting the bosh bands may vary substantially, all prior art techniques have used some means of supporting each bosh band from below. For example, the bosh bands may be provided with outwardly protruding lugs or flanges near the upper edge upon which the above bosh band rests, or the bosh bands may rest upon protruding flanges on the bosh cooling plates which are unifomlly positioned around each group of brick courses.

When the blast furnace is placed into operation, thermal expansion thereof will usually require some form of adjustment in the bosh band supports. For example, it may be necessary to flame cut relief notches between the lower edge of the bosh bands and the supporting lugs or flanges, or it may be necessary to remove previously inserted shims from between the lower edge of the bosh bands and supporting lugs or flanges.

Since the bosh is perhaps the hottest part of the blast furnace, failures in the bosh walls are more frequent than failures in other wall portions, especially in the lower end thereof near the tuyere line. Repair of such failures will not only require removal of the bosh band at the point of repair, but will also require removal or temporary support of all bosh bands thereabove. This results of course because all upper bosh bands are directly or indirectly supported vertically by the bosh band to be removed.

SUMMARY OF THE INVENTION An object of this invention is to overcome the above difficulties by providing a new and improved concept for supporting bosh bands on iron smelting blast furnaces wherein each bosh band is supported from the BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view showing the lower portion of a blast furnace side-wall in radial section which incorporates one embodiment of this invention;

FIG. 2 is an enlarged sectional view of a bosh sidewall showing the bosh band supporting means of FIG.

FIG. 3 is an elevational view of the bosh side-wall shown in FIG. 2;

FIG. 4 is a view substantially like FIG. 2 but showing a different embodiment of the bosh band supporting means; and

FIG. 5 is an elevational view of the bosh side-wall shown in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to FIG. 1, the extreme lower portion of a typical iron smelting blast furnace includes the hearth 10, consisting primarily of the hearth floor 12, and annular hearth side-wall 14, each constructed of refractory bricks and a supporting steel jacket 16 girdling the annular brick side-wall 14. A plurality of tuyere ports 18 are provided radially through the hearth side-wall 14 and jacket 16 into which tuyeres and tuyere coolers (not shown) must be inserted.

As partially described above, the blast furnace bosh 20 rests upon the hearth side-walls 14 and consists of a refractory brick side-wall 22 having a plurality of water cooled bosh cooling plates 24 uniformly distributed therein. The bosh side-wall 22 is formed by laying the bricks and cooling plates 24 in a plurality of groups of annular courses each one on top of another and having a common vertical axis. Each group of brick courses has a slightly larger diameter than the group of courses below thereby providing a widening shaft diameter in the upward direction. Lateral structural support of side-wall 22 is provided by a plurality of bosh bands 26, with one such bosh band 26 girdling the outer periphery of each group of brick courses. Like the brick side-wall 22, each bosh band 26 has a slightly larger diameter than the bosh band therebelow. The height of each bosh band 26 is slightly greater than the height of the group of brick courses it encircles so that adjoining bosh bands 26 slightly overlap. An incombustible, resilient sealant, such as asbestos rope 28 (FIG. 2), is packed within the overlapping portions between bosh bands 26 to seal the furnace against gas leaks.

The bosh cooling plates 24 are usually hollow copper castings horizontally spaced within each group of brick courses and extend radially inward. The outward end of cooling plates 24 are supported by steel collars 30, which are in turn retained within conforming openings in bosh bands 26. Castable refractory material 32 is provided between the cooling plates 24 and the brick side-wall 22 to insure intimate contact of the cooling plates 24 and the brick side-wall 22 and effect maximum extraction of heat from the brick side-wall 22. Suitable water connections (not shown) are fitted to cooling plates 24 to circulate cooling water through each cooling plate 24 when the furnace is in operation.

Blast furnace side-walls above the bosh 20 are usually supported upon the furnace mantle structure 36. The mantle structure 36 is usually supported by a plurality of furnace columns 34, only a part of which is shown in FIG. 1, which encircle the furnace bosh bands 26.

The crux of this invention resides in a hanging type of support means for the bosh bands 26. One embodiment of the bosh band support means is shown in FIGS. 1, 2 and 3, and comprises a plurality of vertically oriented plate steel brackets 40 uniformly distributed around each bosh band 26 near the upper edge thereof. Vertically oriented pairs of parallel hanging steel plate brackets 42 are secured to and extend below the lower edge of each bosh band 26 straddling each bracket 40 on the bosh band 26 therebelow. Each bracket 40 is provided with a vertically and horizontally elongated hole 44 and each bracket 42 is provided with a circular hole 46. Holes 44 and 46 must be aligned to receive a bolt or pin 48. When assembly is complete, brackets 42 will hold bold 48 in a horizontal position so that brackets 40 and, accordingly, the next-lower bosh band 26 will hang therefrom.

The uppermost bosh band 26A is usually permanently suspended from the annular mantle ring structure 36. The lowermost bosh band 26B is provided only with brackets 40. That is to say, bracket pairs 42 are omitted from bosh band 26B because no further bosh bands 26 are suspended therefrom. Rather, bosh band 268 overlaps hearth jacket 16 which is supported by the furnace foundation therebeneath.

In the as-assembled ambient temperature condition, the bosh bands 26 will be supported primarily by the bracketing means as described above. As the furnace is heated for use, bosh brick side-walls 22 will thermally expand appreciably so the bosh bands 26 may be held in place, independent of brackets 40 and 42, by the frictional forces between bosh bands 26 and bosh brick side-walls 22. In addition, the bosh bands 26 will themselves expand thermally both radially and vertically. If the frictional forces between bosh bands 26 and bosh side-wall 22 isv not great, it is readily seen that all bosh bands 26 will hang suspended by the above described bracket system regardless of thermal expansion. If the frictional forces are great, the elongated nature of hole 44 will permit adjoining bosh bands 26 to expand toward each other without the need for adjustment or relief notching. It is obvious therefore that hole 44 should be sufficiently larger than bolt 48 passing therethrough so as to allow ample clearance for thermal expansion.

Because the bosh band support means described above literally hangs the bosh bands 26 one from another, it is readily apparent that should brick side wall repair work be necessary in the lower portion of bosh 20, it is only necessary to remove the bosh bands 26 adjacent to the area needing work, and it is not necessary to remove all bosh bands 26 thereabove. This will greatly simplify repair work in the bosh 20 and substantially shorten down-time. The advantages in the time-saving are apparent when it is realized that to remove a bosh band 26 also requires removal of cooling plates 24 and steel collars 30 inserted therethrough and the cooling water circulation lines (not shown) therearound. Such removal and reinsertion is further complicated by the fact that all the work must be done within the narrow confines between the furnace and the furnace columns 34.

Another embodiment of this invention is illustrated in FIGS. 4 and 5 wherein a plurality of horizontal steel flanges 50, having vertical supports 52, are welded to and spaced around the lower edge of each bosh band 26. A plurality of steel flanges 54, having supports 56, are secured to each bosh band 26 near the upper edge thereof in an aligned mating relationship to flanges 50 on the bosh band 26 thereabove. Vertically aligned holes 58 and 60 are provided through flanges 50 and 54 respectively to receive a bolt 62 to which nut 64 is attached. It is readily seen that each bosh band 26 will hang suspended from the bosh band 26 thereabove via bolts 62 and nuts 64. If preferred, flanges 50 and 54 need not be short segments intermittently spaced around the bands 26 but can each be composed of a single flange encircling the bands 26.

In order to allow sufficient clearance for thermal expansion, there should be suitable clearances between flanges 50 and 54, to provide for vertical expansion and hole 60 should be sufficiently larger than bolt 62 therethrough and elongated radially to allow for differences in radial expansion. It should be apparent that this flange support system will function substantially the same as the bracket support system described previously, allowing for thermal expansion of the bosh bands 26 without the need for adjustment of the supports, and further allowing access to the lower portions of bosh side-wall 22 without the need for removing all bosh bands 26.

Although the two embodiments described above are rather specific, it should be understood that the basic concept of this invention resides generally in the hanging of one bosh band from the bosh band thereabove as opposed to the prior art technique of supporting one on the other, the advantages thereof being to eliminate the need for relief notching or adjusting the supports when the furnace is initially heated and to allow removal of lower bosh bands without the need for removing all bosh bands thereabove. It is apparent therefore that numerous modifications and other embodiments could be employed to accomplish the same end without departing from the basic concept of the invention. All that is necessary is that the uppermost bosh band 26A be supported by furnace members independent of the bosh bands therebelow. This can be done by the described hanger means as shown in FIG. 1, or in any other way held in place independently of other bosh bands 26. Then each lower bosh band 26 must be progressively suspended from the above bosh band by any hanging means or combination of hanger members which will restrict downward motion, and yet having sufficient play or clearances to provide some limited lateral and upward movement thereby allowing for thermal expansron.

I claim:

1. In an iron smelting blast furnace having a plurality of annular bosh bands girdling the refractory walls of the bosh portion of the furnace wherein each bosh bandis slightly larger in diameter than the bosh band therebelow, the improvement comprising means for securing the uppermost bosh band to furnace members independent of the bosh bands therebelow, and hanging means for suspending each lower bosh band from the bosh band thereabove so that all bosh bands hang supported from above, said hanging means including means permitting a limited lateral and upward movement of the bosh bands thereby allowing for thermal expansion thereof.

2. The iron smelting blast furnace of claim 1 in which said hanging means comprise a plurality of upper hanger members secured around and extending outwardly from the lower edge of each but the lowermost bosh band, a plurality of lower hanger members secured around and extending outwardly from the upper edge of each but the uppermost bosh band such that, each lower hanger member is associated with an upper hanger member on the bosh band thereabove, and a supporting member secured between each set of associated upper and lower hanger members to restrict downward motion of the lower hanger member and the bosh band to which it is secured.

3. The iron smelting blast furnace of claim 2 in which each of said hanger members includes an outwardly extending horizontal flange having a hole therethrough aligned with a hole in the associated hanger member, and the supporting member comprises a bolt and nut secured through said holes in the flanges of said associated hanger members.

4. The iron smelting blast furnace of claim 2 in which said upper hanger members comprise substantially outwardly extending vertical brackets arranged in pairs and extending below the lower edge of the bosh band to which they are attached, each bracket having a hole therethrough, said lower hanger members comprise substantially outwardly extending vertical brackets one located between each of said bracket pairs, each of said last named brackets having an enlarged hole therethrough alignable with said holes through the bracket pairs on either side thereof, and said supporting means comprises a bolt secured through all three holes. 

1. In an iron smelting blast furnace having a plurality of annular bosh bands girdling the refractory walls of the bosh portion of the furnace wherein each bosh band is slightly larger in diameter than the bosh band therebelow, the improvement comprising means for securing the uppermost bosh band to furnace members independent of the bosh bands therebelow, and hanging means for suspending each lower bosh band from the bosh band thereabove so that all bosh bands hang supported from above, said hanging means including means permitting a limited lateral and upward movement of the bosh bands thereby allowing for thermal expansion thereof.
 2. The iron smelting blast furnace of claim 1 in which said hanging means comprise a plurality of upper hanger members secured around and extending outwardly from the lower edge of each but the lowermost bosh band, a plurality of lower hanger members secured around and extending outwardly from the upper edge of each but the uppermost bosh band such that each lower hanger member is associated with an upper hanger member on the bosh band thereabove, and a supporting member secured between each set of associated upper and lower hanger members to restrict downward motion of the lower hanger member and the bosh band to which it is secured.
 3. The iron smelting blast furnace of claim 2 in which each of said hanger members includes an outwardly extending horizontal flange having a hole therethrough aligned with a hole in the associated hanger member, and the supporting member comprises a bolt and nut secured through said holes in the flanges of said associated hanger members.
 4. The iron smelting blast furnace of claim 2 in which said upper hanger members comprise substantially outwardly extending vertical brackets arranged in pairs and extending below the lower edge of the bosh band to which they are attached, each bracket having a hole therethrough, said lower hanger members comprise substantially outwardly extending vertical brackets one located between each of said bracket pairs, each of said last named brackets having an enlarged hole therethrough alignable with said holes through the bracket pairs on either side thereof, and said supporting means comprises a bolt secured through all three holes. 